Ocular Anatomy Flashcards
What are the 7 layers of the eyelid?
- Skin
- Subcutaneous Areolar
- Orbicularis
- Submuscular Areolar
- Orbital Seption
- Posterior Muscular
- Tarsal Plate
- Palpebral Conjunctiva
What is telecanthus?
Abnormally increased distance b/n the medial canthi of the lids
Trichiasis is secondary to what?
Entropion
What is Phthiriasis palpebrarum is caused by?
infections of lashes caused by phthirus pubis
The skin layer contains what 3 things?
- Fine hairs
- Sweat glands
- Sebaceous glands
Where is the thinnest skin layer of the body?
Eyelid
T/F the skin layer of the eyelid contains fat?
False
What kind of CT is found in the subcutaneous and submuscular areolar layer?
Loose CT
What structure can be found in the subcutaneous layer of the eyelid?
Levator aponeurosis
What structure does the orbicularis layer of the eyelid contain?
Palpebral portion of the orbicularis oculi
What nerve innervates the Orbicularis Oculi?
CN7
What is the orbital portion of the Orbicularis Oculi in charge of?
Forced blinks
What is the palpebral portion of the Orbicularis Oculi in charge of?
Spontaneous and reflex blinking
What are the two portions of the palpebral portion of the Orbicularis Oculi?
- Muscle of Riolan (pars ciliaris)
2. Muscle of Horner (pars lacrimalis)
The muscle of Horner is in charge of?
Tears: encircles canaliculi to help drain tears
The muscle of Riolan is in charge of?
Roll: rotating lashes
Tide: keeps it tight
Divide: gray line
Paralysis of the orbicularis will eventually result in a condition known as..?
Ectropion: lower lid droops away from globe
What structures does the submuscular areolar layer contain?
Upper: Levator aponeurosis
Palpebral potion of the main lacrimal gland
Upper and Lower: Peripheral and Marginal arcades
What are four pertinent negatives that you should have for orbital cellitus?
- Fever
- Decreased Vision
- EOM restriction
- Pain
What kind of CT is the orbital septum?
Dense Irregular CT
What are the function(s) of the orbital septum
- Barrier to the orbit in the upper and lower lids
- Prevents fat from falling down onto lid margins
- Keeps infection localized to anterior portion of the eyelid, away from the orbit
What meds would you give for Orbital Cellulitis?
NOTE: polymicrobial (staph & strep)
- Augmentin: cell wall synthesis inhibitor
- Cephalexin: cell wall synthesis inhibitor
- Azithromycin: 50S subunit
- Doxycycline: 30S
- Fluroquinolones: DNA synthesis inhibitor
What becomes the orbital septum?
Peri-orbita: loosely covers orbital bones
What is the orbital septum continuous with?
Periorbita and periosteum of skull
What attaches to the orbital septum medially
Posterior Lacrimal Crest
Does the orbital septum protect the lacrimal sac from infection?
Yes - Located posterior
What layer is the insertion site of the levator aponeurosis?
Superior Orbital Septum
What structures are in the posterior muscular layer?
- Superior levator Palpebrae
2. Muller’s muscles (superior and inferior)
Superior Levator Palpebrae originates from where?
Lesser wing sphenoid
What is the function of the Superior Levator Palpebrae?
Main retractor of upper lid
What is Whitnal’s ligament?
Fulcrum of the Superior Levator Palpebrae that allows muscle to change course from anterior posterior to superior inferior
What is the Levator aponeurosis?
Fanned shaped tendon of Superior Levator Palpebrae that attaches to skin and anterior surface
What does the levator aponeurosis attach to (3 places)
- Skin
- Orbicularis/Subcutan
- Tarsal plate
Where is the attachment of the levator aponeurosis to the skin of upper lid form?
Superior palpebral furrow
Where does the lateral horn of the levator aponeurosis attach to?
Whitnal ligament
Where does the medial horn of the levator aponeurosis attach to?
medial palpebral ligament
How is the inferior palpebral furrow formed?
Indirect attachment of the inferior rectus muscle into skin
What does the eyelid furrows separate?
Tarsal and orbital portions of lid
Muscle of Muller is what kind of muscle?
Smooth Muscle
Muscle of Muller has what kind of receptors and is innervated by what?
A2
Sympathetic nervous system
Where does the inferior tarsal muscle originate from?
Fascial sheath of inferior rectus
Horner’s syndrome is a DEC in which innervation?
Sympathetic
What is happening when the lid is retracted back too much
- Too much sympathetic (overaction of mueller)
2. Thyroid issue
When you hear Thyroid eye disease, what should you think?
Fibroblast proliferation
What is a normal Interpalpebral fissure distance?
10-12
Tarsal plate is made of what kind of connective tissue
Dense irregular
Tarsal plate structure
Horizontal and vertical collagen fibrils that surround meibomian glands